Morris Water MazeSpatial memory was tested in a Morris water maze setup. Before testing, mice were handled for at least 5 days, until they did not try to jump of or walk from the experimenters hand. A circular pool (diameter 125 cm) was filled with water (30 cm below the rim) which was painted white with non-toxic paint and kept at a temperature of 25 degrees C. An escape platform (diameter 9 cm) was placed at 30 cm from the edge of the pool submerged 1 cm below the water surface. Visual cues were located around the pool at a distance of ca. 1.5 m. During testing lights were dimmed and covered with white sheets and mice were video-tracked using ViewerII (Viewer 2, BIOBSERVE GmbH, Bonn, Germany). Mice were trained for 5 consecutive days, 2 sessions of 2 trials per day with a 1-3 min inter-session interval. In each trial, mice were first placed on the platform for 30 s, and then placed in the water at a random start position and allowed a maximum of 60 s to find the platform. Mice that were unable to find the platform within 60 s were placed back on the platform by hand. Within each 2-trial session, after 30 s on the platform mice were tested again. On day 5 or 6 a probe trial was performed with the platform removed. Mice were placed in the pool opposite from the platform location and allowed to swim for 60 s. During training trials, the latency, distance and speed to reach the platform were measured; in the probe trial, the time spent and distance traveled in each quadrant of the pool were measured, as well as the number of platform-zone crossings.